Glial <i>betaPix</i> is essential for blood vessel development in the zebrafish brain.

Abstract

The formation of blood-brain barrier and vascular integrity depends on the coordinated development of different cell types in the brain. Previous studies have shown that zebrafish <i>bubblehead</i> (<i>bbh</i>) mutant, which has mutation in the <i>betaPix</i> locus, develops spontaneous intracerebral hemorrhage during early development. However, it remains unclear in which brain cells <i>betaPix</i> may function. Here, we established a highly efficient conditional knockout method in zebrafish by using homology-directed repair-mediated knockin and knockout technology and generated <i>betaPix</i> conditional trap (<i>betaPix^ct</i>) allele in zebrafish. We found that <i>betaPix</i> in glia, but neither neurons, endothelial cells, nor pericytes was critical for glial and vascular development and integrity, thus contributing to the formation of blood-brain barrier. Single-cell transcriptome profiling revealed that microtubule aggregation signaling stathmins and pro-angiogenic transcription factors <i>Zfhx3/4</i> were downregulated in glial and neuronal progenitors, and further genetic analysis suggested that betaPix may act upstream on the PAK1-Stathmin and Zfhx3/4-Vegfaa signaling to regulate glia migration and angiogenesis. Therefore, this work reveals that glial <i>betaPix</i> plays an important role in brain vascular development in zebrafish embryos and possibly human cells.